I know this, but I know Rick did and yourself and the Getrdunn said it would never make the power.. People never post the facts or specs....they always assume its the engine builders fault. When you upgrade your engine, its not just going to run faster...there's always more work that needs to be done to compliment the engine. I hope you didn't take what I said in a mean demeanor, its just you always see people post stuff like this and most don't know what they are talking about and are the guys who believe the magazines....

I have the dyno in a PDF format if someone knows how to post it, I cant figure it out for the life of me If so, post your email and you can post it for me.

As far as the hypereutectic opinions...tell that to the thousands of other boaters with similar combinations, more power and the same pistons. On my 26ft Sleekcraft I ran a similar setup with slighly more power, same compression and pistons and it lasted me about 300hrs before I decided to freshen her up. We have sold dozens of these in the last couple years and not a call back on this engine. Its not meant to be a racer, just an upgrade. We do call for 92 octane or better...so as long as its not lower they should be fine.

If I were him at this point is pull the heads and do some creative bowl work. If he could get the cc's up to about 125 or so he would probably be OK. As we all know marine engines are under a continuous load in comparrison to that of a street engine. Personally I would never go any higher than 9.5 to 1 with iron heads. Even though you have good intentions of filling on land there always seems to be that time where your stuck with what you have available on the water.

I have the dyno in a PDF format if someone knows how to post it, I cant figure it out for the life of me If so, post your email and you can post it for me.



Send it to me and I will get it posted.
[email protected]

Original question i'd use 750 marine carb i wouldn't go boating with an auto car. Burning fiberglass blows I agree with Griff, young and Getrdunn on the rest. To much CR on a marine engine, with that timing i'd think she will rattle to destruction. Evenly as possible open up some more the head chamber CC's and back the timing down. With a two bolt block and the KB pistons, drop your WOT RPM range. On your next build try something like griff's spec's or look up some of youngs stuff, I have also built several similar to this and they scream. Your next build think roller cam with a good lobe seperation. Short boating seasons and winterizing hates flat tappets. Marine BBC love easy CR and split duration rollers. Forged pistons in a marine engine, total load off idle to WOT. Not bashing your engine guy, if you leave it as is, change timing and make sure you keep it richer than lean!!

dyno sheet

Nice job... Surprised to see the torque only drops off just over 50 ft pds from peak (4,200) to desired running RPM at 5,200/peak HP. A good rule of thumb is to have Max running RPM 800 to 1,000 over peak torque, which in this case is right there. Nice conservative package, good torque curve.

Here is a formula to help you figure out what carb size you need. I'm sure some people will disagree, but I've been told this formula buy more than one good engine builder. I hope I made it easy to understand!
Take your engine size and divide it by 8 (454/8= 56.75)
Then take that number an multiply by 4 (4x56 = 227 cubic inches) 4 is used becuase this is the number of cylinders drawing from the carb with every revolution of the crank.
Now take your cubic inch number (227) and convert it into cubic feet. So divide (227/1728= .1312)
Your almost there- take the .1312 cu ft number and muliply it by the rpms you will be spinning. And that is the carb size you will need to run. Note this is for a theretical engine that has 100% volumetric effeciency! Which for that to happen your exhaust would need to be working at 100%! This is HIGHLY unlikely, 80-90% is more case. So as you can see you really don't need a big carb. Below are some rpm carb size suggestions for your 454
4900- 650 cfm
5100- 700 cfm
5700- 750 cfm

Thanks for posting up the dyno and the props We have been testing other packages with these heads...these are basically untouched 781 heads..the other engines we are releasing are 454-505ci Hyd Roller cams, worked over 781 heads pushing 600+ HP for a reasonable cost.

I've never had much faith in carb calculators however I would have to say this actually seems to be closer to that of the old theory. Surprized I haven't seen this one before. Makes a little more sense. Like I said earlier, learn something new every day..

They don't know how to spec I/O marine engines yet. Their 540cid 600hp engine has too much camshaft and too big of cylinder heads. How else would a 540cid with Dart Pro 1's only make 600hp and not run well to boot?

I've been following their marine builds (and believe it or not their questions to fellow forum members) all over the net and don't know why they come up with the parts combo's they do.

Not bashing, just my presence and data collecting. It is what it is and they are who they are.